A data center refers to processing functionality for performing one or more prescribed processing tasks. In one common application, for example, a provider may use a data center to implement any kind of network-accessible service (such as an Email service, search service, and so on). In some cases, the provider may use a specially designed computer room within a general purpose facility to implement the data center. For a particularly large-scale service, the provider may devote one or more separate facilities to implement the data center.
The provider commonly places a high priority on delivering a reliable service. To this end, the provider may design the data center to minimize the number of errors that affect the service. It is believed that the environment in which the data center operates may sometimes cause or contribute to data processing failures. Hence, the provider commonly designs the data center to operate in a tightly controlled environment. For example, the provider may design its data center to operate within prescribed temperature and humidity ranges. This goal can be accomplished using various types and combinations of cooling systems, such as Computer Room Air Conditioning (CRAC) systems, chillers, and so on. However, failures will still occur. To address these events, the provider may design the data center to allow an administrator to locate and replace failed components and also perform regular maintenance.
A provider faces various challenges in designing a data center. One such challenge pertains to the cost of initially constructing and periodically upgrading the data center. This cost includes building structure costs, cooling system costs, processing functionality costs, and so on. Another challenge relates to the cost of operating the data center. A significant aspect of operating cost relates to the power required to run the data center facility. This cost has two components. A first component relates to the cost of running the processing functionality used to deliver the service. A second component relates to the cost of running all other functions performed by the data center, such as cooling, lighting, and so forth. The overall efficiency of the data center is defined by the ratio of the total power consumed by the data center to the power consumed by the processing functionality. The parameter is referred to as the Power Usage Effectiveness (PUE). For example, some data centers operate with a PUE of approximately 2 or higher; others have somewhat better performance. Other operating costs of a traditional data center relate to manual activities, such as the costs involved in identifying and replacing failed components.
As to power-related costs, the power consumed by data processing equipment has increased over time. However, the sophistication of the equipment has likewise increased. As a result, the overall performance per unit of energy consumption of some equipment has increased over time. On the other hand, the power consumed by other infrastructure functions continues to rise.